Tempering of glass

H. Ohkubo and S. Nishio, Mist Cooling for Thermal Tempering of Glass, in P. J. Marto and I. Tanasawa (eds.), Proceedings of the 1987 ASME-JSME Thermal Engineering Joint Conference, 5, pp. 71-78, ASME, New York, 1987. 

Incorporation of an outer layer having a lower coefficient of thermal expansion, as in glazing or tempering of glass. These will be discussed in greater detail in Chap. 13. 

Residual stresses are generally deleterious to the mechanical properties and should be avoided. This is especially true if a part is to be subjected to thermal cycling. In some situations, however, residual stresses can be used to advantage. A case in point is the transformation toughening of zirconia discussed in Chap. 11, and another excellent example is the tempering of glass discussed in the next section. 

Surface defects are responsible for the limited glass resistance and its large scatter [6]. The creation of a compressive stress layer in the surface of the material can limit the formation or propagation of flaws and improve the mechanical properties thermal and chemical tempering of glass are two main methods for producing a compressive stress in the glass surface. The thermal method is widely used to make windows and other transparent flat structural components [2, 7],... 

Tempering of glass has been well established for decades but very little work has been done in the area of container glass. This is due to the difficulties associated with rapidly cooling the inside surfaces of the container through the limited opening of the finish, the wall thicknesses and variations thereof, and due to the complex geometries involved. 

R. Gardon, Thermal Tempering of Glass, Glass Science and Technology V. Academic Press, New York. (1980)... 

---